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United States Patent |
5,120,314
|
Greenwood
|
June 9, 1992
|
Single use hypodermic syringe
Abstract
A single use hypodermic syringe uses a generally cylindrical elongated
syringe body defining a center bore and supporting a hollow needle in
communication with the center bore through the inlet/output channel. A
movable piston formed of an elastic material is sealingly supported within
the syringe bore. A piston driver member extends into the syringe bore and
is coupled to the piston. An annulus ring is fixed within the center bore
near the inlet/outlet channel. The annulus permits the piston to pass over
it when delivering an injection but locks onto the piston at the
completion of the injection, precluding any further use of the syringe.
Inventors:
|
Greenwood; Eugene C. (2956 Peppertree La., Apt. B, Costa Mesa, CA 92626)
|
Appl. No.:
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673951 |
Filed:
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March 22, 1991 |
Current U.S. Class: |
604/110; 604/220 |
Intern'l Class: |
A61M 005/00 |
Field of Search: |
604/110,218,220,111,187
|
References Cited
U.S. Patent Documents
4713056 | Dec., 1987 | Butterfield | 604/110.
|
4986812 | Jan., 1991 | Perler | 604/220.
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5000737 | Mar., 1991 | Free et al. | 604/218.
|
5021047 | Jun., 1991 | Movern | 604/110.
|
Primary Examiner: Yasko; John D.
Claims
What is claimed is:
1. A single use syringe assembly having misuse resistant features
comprising;
a. a barrel having an inside surface describing a chamber for retaining
fluid, said barrel having an open barrel end and a distal barrel end
having a passageway therethrough in fluid communication with said chamber;
b. a piston driver including an elongate body portion having a proximal end
and a distal end, said distal end being attached to an elastic piston,
said piston being slidably positioned in fluid tight engagement in said
barrel, said body portion of said piston driver extending proximally from
said open barrel end;
c. an annulus fixedly placed within said barrel, with one or more integral
projections thereon facing in the distal direction, the front face of said
projections located at a distance equal to 5 percent to 100 percent of the
axial length of said piston from said distal barrel end, said projections
being angled inward toward the axial centerline of said syringe at an
angle between 1.degree. and 45.degree. which will permit all or part of
said piston to pass said projections when said piston is being advanced in
the distal direction to said distal barrel end, but when said piston
driver is subsequently urged in the proximal direction, said projections
engage the piston, preventing proximal movement;
d. Said annulus contains one or more integral proximally facing projections
which are angled outwardly from the axial centerline of said syringe at
1.degree. to 30.degree. which brings them into contact with said inside
surface of said barrel, permitting said annulus to slide across said
inside surface of said barrel when it is urged in a distal direction but
when said annulus is urged in a proximal direction, said projections
engage said inside surface of said barrel, preventing proximal movement of
the annulus.
2. The syringe assembly of claim 1 wherein said annulus is positioned and
affixed against distal motion by one or more distally facing projections
which abut said barrel end.
3. The syringe assembly of claim 1 wherein said annulus is affixed to said
barrel inside surface by bonding means.
4. The syringe assembly of claim 1 wherein said annulus is composed of
corrosion resistant metal.
5. The syringe assembly of claim 4 wherein said corrosion resistant metal
is 0.020 inches or less in thickness.
6. The syringe assembly of claim 1 wherein said annulus is composed of
plastic.
7. The syringe assembly of claim 1 wherein said annulus has means wherein
it can expand or contract in diameter for adapting to variations in the
diameter of said barrel inside surface.
8. A single use syringe assembly having misuse resistant features
comprising;
a. A barrel having an inside surface describing a chamber for retaining
fluid, said barrel having an open barrel end and a distal barrel end
having a passageway therethrough in fluid communication with said chamber;
b. a piston driver including an elongate body portion having a proximal end
and a distal end, said distal end being attached to an elastic piston,
said piston driver body including a pushing flange adjacent said piston,
said piston being slidably positioned in fluid tight engagement in said
barrel, said body portion of said piston driver extending proximally from
said open barrel end;
c. an annulus fixedly placed within said barrel, with one or more integral
projections thereon facing in the distal direction, the front face of said
projections located at a distance exceeding the length of the piston plus
the length of the piston pushing flange of the piston driver from the
distal end of said barrel inside surface, said projections being angled
inward toward the axial centerline of said syringe at an angle between
1.degree. and 45.degree. which will permit said piston and said pushing
flange to pass said projections when said piston is being advanced in the
distal direction to said distal barrel end, but when said piston driver is
susequently urged in the proximal direction, said projections engage the
piston pushing flange, preventing its proximal movement;
d. said annulus is positioned and affixed against proximal motion by one or
more integral proximally facing projections which are angled outwardly
from the axial centerline of said syringe at 1.degree. to 30.degree. which
brings them into contact with said inside surface of said barrel,
permitting said annulus to slide across said inside surface of said barrel
when it is urged in a distal direction but when said annulus is urged in a
proximal direction, said projections engage said inside surface of said
barrel, preventing proximal movement of the annulus.
9. The syringe assembly of claim 8 wherein said annulus is positioned and
affixed against distal motion by one or more distally facing projections
which abut said barrel end.
10. The syringe assembly of claim 8 wherein said annulus is affixed to said
barrel inside surface by bonding means.
11. The syringe assembly of claim 8 wherein said annulus is composed of a
corrosion resistant metal.
12. The syringe assembly of claim 11 wherein said corrosion resistant metal
is 0.020 inches or less in thickness.
13. The syringe assembly of claim 8 wherein said annulus is composed of
plastic.
14. The syringe assembly of claim 8 wherein said annulus has means wherein
it can expand or contract in diameter for adapting to variations in the
diameter of said barrel inside surface.
Description
FIELD OF THE INVENTION
This invention relates generally to hypodermic syringes and particularly to
a single use syringe incapable of multiple use.
BACKGROUND--CROSS REFERENCE TO RELATED APPLICATIONS
The present invention relates to standard plastic hypodermic syringes. The
inventor of the present invention has been a participant in two related
patents, U.S. Pat. Nos. 4,923,443 and 4,950,240 in which a connection
between the piston and piston driver is broken or cut when the piston is
driven forward to deliver the injection, thus preventing the syringe from
being used to give a second injection. Although the object of the previous
inventions is the same as the present invention, the present invention
bears virtually no actual resemblance to the patents listed above.
BACKGROUND OF THE INVENTION
The present invention relates to standard plastic hypodermic syringes.
Although the standard disposable hypodermic syringe is intended to be used
once and discarded, it is possible to use the syringe many times. When a
standard hypodermic syringe falls into the hands of drug addicts, it is
frequently used by two or more addicts to give multiple injections without
sterilizing, thereby transfering any infectious disease one might have to
the other. This practice has led to a serious increase in AIDS cases.
Many attempts have been made to invent a hypodermic syringe which could be
used only once. As an example, Wozniak et al. in U.S. Pat. No. 4,781,683
teaches a single use syringe which is automatically rendered inoperative
when a fluid containing water is drawn into the syringe. This is
accomplished by incorporating a hydrophilic insert into the internal wall
of the syringe body at the narrow inlet/outlet channel of the syringe.
When this insert is contacted by a fluid containing water, it absorbs some
of the water and swells in size, closing off the passage.
An additional single use syringe is taught by Trenner in U.S. Pat. No.
4,781,684 in which an annular groove is provided near the discharge end of
the syringe barrel which has a diameter greater than the interior diameter
of the barrel. A locking element located between the piston and piston
driver has an outside diameter which is greater than the inside diameter
of the barrel. When the fluid is fully expelled from the syringe, the
locking element engages the annular groove, preventing withdrawal of the
piston.
Another single use hypodermic syringe is taught by Kosinski in U.S. Pat.
No. 4,961,728. Kosinski inserts a locking element between the syringe
barrel and the piston driver, positioned between the specially constructed
structural flutes of the piston driver. As the piston driver moves in a
distal direction, the barbs of the locking element slide along the inside
surface of the barrel, but when there is proximal movement, the barbs dig
in and prevent movement of the piston driver in the proximal direction,
thereby preventing its use in giving a second injection.
While the foregoing described prior art devices provide some protection and
increased safety of the use of the hypodermic syringe and some protection
of the reuse thereof, they always render the hypodermic syringe much more
costly to manufacture and more cumbersome to use.
There remains, therefore, a need in the art for a convenient to use,
inexpensive to manufacture hypodermic syringe which is limited to a single
use. Additionally, there remains the need for an inexpensive device which
can be added to any existing hypodermic syringe which will make it into a
single use syringe.
SUMMARY OF THE INVENTION
Accordingly, it is the object of the present invention to provide an
improved hypodermic syringe. It is a more particular object of the present
invention to provide an improved hypodermic syringe designed for a single
use. It is a still more particular object of the present invention to
provide an improved hypodermic syringe for single use which is
automatically rendered inoperable following its first use. In addition, it
is a particular object of the present invention to provide an improved
hypodermic syringe which requires no dimensional modification of the basic
parts of the standard disposable hypodermic syringe, permitting only a
slight increase in manufacturing cost and scheduling. It is a further
particular object of the present invention to provide an improved
hypodermic syringe in which an off-the-shelf syringe can be automatically
rendered incapable of giving a second injection by the addition of a
simple auxiliary part.
In accordance, there is provided a metal annulus which is positioned within
the interior front of the barrel of a standard hypodermic syringe which
allows usage as a standard hypodermic syringe but when the hypodermic
syringe is activated to a closed position completing the first injection,
the annulus automatically locks onto the piston or piston driver,
preventing the syringe from being reused to give another injection.
For the purpose of the description of the present invention, the term
"distal end" refers to the end farther from the person holding the syringe
in the inject position and the term "proximal end" refers to the end
closer to the holder of the syringe.
A standard hypodermic syringe assembly has a cylindrical barrel having an
inside surface describing a chamber for containing fluid, an open barrel
end, and a distal barrel end having a narrow passageway which communicates
with the hollow needle. A piston driver having a proximal and a distal end
moves within the barrel. The distal end of the piston driver is attached
to the proximal end of an elastic piston which is slidably positioned in
fluid tight engagement in the barrel. Abutting the proximal end of the
piston, the piston driver has a face which pushes on the piston when
driving the piston toward the distal end of the syringe barrel. The piston
driver also has an attachment inside the piston for pulling the piston in
the proximal direction. The proximal end of the piston driver extends out
through the open end of the syringe barrel and end with a flange which can
be grasped with the fingers and/or thumb for the purpose of drawing fluid
through the needle and into the barrel and for then forcing the fluid out
through the needle.
Into this standard hypodermic syringe, close fitting to the inside wall of
the barrel, the present invention places a thin, hard cylindrical annulus
of narrow axial width at the distal end of the syringe barrel. The annulus
has one or more outward facing sharp edged flexible projections which face
in the proximal direction and are angled so that when being placed in the
syringe barrel they can slide into the barrel from the proximal end to the
distal end but will dig into the inside of the barrel and lock against any
attemped movement in the opposite direction. Another part of the annulus
is one or more inwardly facing projections which are angled such that the
elastic piston will easily pass over them when moving in the distal
direction to the distal end of the barrel when giving an injection, but
the inward facing projections will lock onto the piston and prevent its
movement relative to the annulus when the piston is attemped to be moved
in the proximal direction after giving the injection. Thus, with the
annulus locked against the inside wall of the barrel in a manner which
prevents proximal movement and the piston locked against proximal movement
by the annulus, motion of the piston in the proximal direction relative to
the barrel is prevented, precluding the use of the syringe in giving a
second injection.
Another feature of the present invention is means which allow the annulus
to be compressed or expanded in diameter, thus making it possible to adapt
to variations in the barrel inside diameter.
Another embodiment of the present invention in a standard disposable
hypodermic syringe assembly is a thin, hard annulus similar to that
described above, but which is bonded in place near the distal end of the
inside of the syringe barrel instead of being locked by the proximal
outward facing projections.
An advantage of the narrow axial width of the annulus is that it presents
only a slight obstruction to the view through the syringe barrel of the
fluid within.
Another advantage in the construction of the annulus is its thin material
thickness which, when placed in a standard hypodermic syringe, displaces
only a very small volume within the fluid containment chamber in the
syringe. Naturally, in syringes originally manufactured with the annulus
in place, the volume marking label can be modified to correct for the
reduced volume due to the annulus.
In a product whose production quantities number in the millions of units
per day, being able to insert the annulus into a standard hypodermic
syringe without modification of the syringe and the molds for their
manufacture is a major advantage in cost conservation. This also
contributes greatly to the speed and simplicity of conversion to the
single use mode.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the present invention, which are believed to be novel, are
set forth with particularity in the appended claims. The invention,
together with further objects and advantages thereof, may best be
understood by reference to the following description taken in conjunction
with the accompanying drawings, in the several figures of which like
reference numerals identify like elements and in which:
FIG. 1 sets forth a partially sectioned side view of a hypodermic syringe
in the partially opened position constructed in accordance with the
present invention;
FIG. 2 sets forth a view of the annulus of the present invention;
FIG. 3 sets forth a partially sectioned view of the present invention with
the annulus in place in the distal end of the syringe barrel;
FIG. 4 sets forth a partially sectioned side view of the present invention
hypodermic syringe in the locked position after delivering an injection;
FIG. 5 sets forth an enlarged section view of the present invention taken
along section line 5--5 showing the piston engaged by the annulus;
FIG. 6 sets forth a partial section view of an alternate embodiment of the
present invention showing the annulus bonded in place within the syringe
barrel;
FIG. 7 sets forth a view of an alternate embodiment of the present
invention annulus incorporating expansion/contraction means for adapting
to varying dimensions of the syringe barrel. Also shown is an alternate
embodiment of the anchoring tabs of the annulus;
FIG. 8 sets forth a partial section view looking in the proximal direction
from the distal end of the present invention hypodermic syringe barrel,
showing an annulus with five locking tabs in position in the syringe
barrel;
FIG. 9 sets forth a partial section view of the distal end of the present
invention hypodermic syringe barrel taken along section line 9--9 showing
a type of expansion/contraction means.
FIG. 10 sets forth a partial section view of an alternate embodiment of the
present invention showing the annulus locking against the piston pushing
flange of the piston driver.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 sets forth a partial section view of a hypodermic syringe 10
constructed in accordance with the present invention. Syringe 10 includes
an elongated generally cylindrical syringe body 11 defining a flange 15 at
one end and a taper 13 at the other end. Syringe body 11 further defines
an interior generally cylindrical syringe bore 14 extending from flange 15
to a funnel end 20. A needle retainer 21 is formed at the distal end of
syringe body 11 proximate taper 13 and in turn supports an elongated
hollow needle 22 defining a point 23. A passage 24 defined within syringe
body 11 extends from funnel end 20 to needle retainer 21 and provides
communication between needle 22 and bore 14.
A piston driver 30 is formed of a quartet of outwardly extending rib
members 31, 32, 33 and 34 (The latter not shown). Ribs 31 through 34 are
commonly joined and generally perpendicularly arranged to provide an
elongated rigid member capable of supporting substantial tension and
compression forces. Piston driver 30 further defines a gripping flange 35
and a piston pushing flange 36 at opposite ends of ribs 31 through 34. A
generally planar cylindrical retractor flange 37 is joined to retractor
shaft 38 within cavity 43 of piston 40, captivating piston 40 on the
distal end of piston driver 30. Syringe body 11 and piston driver 30 are
molded from a plastic material such as polypropylene.
Piston 40, formed of a resilient elastic material such as rubber, defines a
pair of outwardly extending entending sealing lobes 41 and 42 which form
fluid tight contact with the interior of bore 14. Piston 40 further
defines an interior cavity 43.
Within syringe bore 14 at funnel end 20 and in slidable close contact with
syringe bore 14 is annulus 50, made of a hard, thin material such as
stainless steel.
FIG. 2 sets forth a view of annulus 50 constructed in accordance with the
present invention. A typical material for annulus 50 is cold drawn type
304 stainless steel, 0.010 in thickness. Total axial length of the annulus
including tabs is around 0.24 inches. Clearance between the outside
diameter of annulus body 54 and syringe bore 14 is 0.000 to 0.005 inches.
As shown in FIG. 3, an integral part of annulus 50 and extending in the
distal direction are three locating tabs 51 spaced radially at equal
distances and in contact with funnel end 20 of syringe bore 14. Locating
tabs 51 are parallel to the axial centerline of the syringe and in light
contact with the syringe wall. Locating tabs 51 are approximately 0.09
inches in width and 0.12 in axial length.
An integral part of annulus 50 and spaced equally between locating tabs 51
and extending in the distal direction are three locking tabs 52 of 0.06
inches in axial length and 0.09 in width which are angled inward toward
the axial centerline of the syringe at a 15.degree. angle. The distal ends
57 of locking tabs 52 are at a distance from the distal ends of locating
tabs 51 slightly greater than the axial length of sealing lobe 42 of
piston 40. This distance is approximately 0.06 inches.
Facing in the proximal direction and axially in line with locking tabs 52
are three anchoring tabs 53 of approximately 0.05 inches in axial length
and around 0.09 inches in width. Anchoring tabs 53 are angled outward from
syringe axial centerline at a 7.degree. angle, thus bringing them in
spring tight contact with the syringe bore 14. Annulus body 54 of which
all tabs are an integral part is approximately 0.07 in axial length. The
total axial length of annulus 50, including tabs, is around 0.24 inches.
The function of annulus 50 is as follows: when an injection is completed,
piston 40 passes over annulus 50 to funnel end 20. As piston 40 passes
over annulus 50, the locking tabs 52 will bend down some and sealing lobe
42 will deform some, allowing sealing lobe 42 to pass over the locking
tabs. The piston is of such dimension and design that sealing lobe 41 is
in full contact with the syringe wall 14 at all times, preventing fluid
leakage from escaping past piston 40. Once piston 40 reaches funnel end
20, it cannot be withdrawn because the front edges of locking tabs 52 now
dig into elastic piston 40. Any attempt to move locking tabs 52 in the
proximal direction is prevented because anchoring tabs 53 dig into the
plastic syringe wall 14 and prevent proximal movement. Since all tabs are
part of annulus 50 and locking tabs 52 and anchoring tabs 53 are axially
aligned and opposed on annulus 50, they effectively lock piston 20 in
place at the distal end of syringe barrel 14.
FIG. 4 is a partial section view of hypodermic syringe 10 shown in the
closed position after giving an injection.
FIG. 5 sets forth an enlarged view of the distal end of syringe bore 14
taken along section line 5--5. Once piston 40 reaches funnel end 20, it
cannot be withdrawn because the front edges of locking tabs 52 now dig
into elastic piston 40 behind lobe 42. Any atttempt to move locking tabs
52 in the proximal direction is prevented because anchoring tabs 53 dig
into the plastic syringe bore 14 and prevent movement. Since all tabs are
part of annulus 50 and locking tabs 52 and anchoring tabs 53 are axially
aligned and opposed on annulus 50, they effectively lock piston 40 in
place at the distal end of the syringe barrel.
OPERATION
In operation, syringe 10 is delivered in a sterile package with piston 40
located in the partially opened position, approximately 3/8 inch away from
funnel end 20. Annulus 50 is in place against funnel end 20 and in front
of piston 40.
Syringe 10 is removed from the package and needle 22 is inserted into a
medicine vial. Pulling back on gripping flange 35 of piston driver 30
draws liquid from the vial through the needle and into the syringe. When
it appears that more than enough fluid for the prescribed injection has
been drawn into the syringe, piston 40 is cycled back and forth to drive
any air out of syringe body 11 and into the vial. Piston 40 and piston
driver 30 may be cycled in and out as often as desired as long as any part
of sealing lobe 42 does not pass across locking tab 52. Excess medicine is
driven back into the vial and piston 40 is stopped at the point where the
desired amount of medicine is in front of it. The needle is withdrawn from
the vial and the injection given to the patient, pushing the rubber piston
40 to the funnel end 20, exhausting all of the medicine. At this point it
is locked in place and cannot be used again. FIG. 6 sets forth a partial
section view of an alternate embodiment of the present invention showing
annulus 60 bonded in place at a location near funnel end 20 of syringe
bore 14. Bonding in this position eliminates the need for the anchoring
tabs of the preferred embodiment of FIG. 2. Three locking tabs 62 extend
in the distal direction from annulus body 64 for 0.06 inches in axial
length and are angled at 15.degree. toward the axial centerline of syringe
10. The distal ends 67 of locking tabs 62 are located at a distance from
funnel end 20 of syringe bore 14 slightly greater than the axial length of
sealing lobe 42 of piston 40. This distance is approximately 0.06 inches.
Annulus 60 is bonded, cemented or sonic welded to syringe bore 14 at this
location. In this fixed location, it permits sealing lobe 42 of piston 40
to pass over locking tabs 62 when moving in the distal direction but
prevents its moving in the proximal direction when the locking tabs 62
embed themselves in sealing lobe 42. At 66, annulus is rounded or angled
to permit piston 40 to pass over it smoothly.
FIG. 7 sets forth an alternate embodiment of annulus 70, wherein
expansion/contraction joint 77 is incorporated in the body 76 of annulus
70, permitting it to increase or decrease in diameter to accomodate
variations in diameter of syringe bore 14. Since syringe body 11 is molded
plastic, syringe bore 14 is often slightly tapered making for a variation
in diameter from the proximate end to the distal end at funnel end 20.
Some models of hypodermic syringe 10 incorporate a ridge near the
proximate end of syringe bore 14, and the ability of the alternate
embodiment of annulus 70 to vary in diameter permits it to adapt to these
variations and still maintain close contact with syringe bore 14 when
located in its final position.
Also shown in FIG. 7 are five locking tabs 72, which exemplifies the fact
that their quantity may be varied. Also shown is a variation of the
anchoring tabs 73 wherein they are merely outward extending sections of
annulus body 76 which dig into syringe bore 14, preventing movement of
annulus 70 in the proximal direction. Three locating tabs 71 are shown.
FIG. 8 sets forth a partial section end view of syringe body 14 looking in
the proximal direction from funnel end 20. Annulus 70 is shown in contact
with syringe bore 14. Locking tabs 72 are shown extending inwardly toward
the axial centerline of syringe bore 14.
FIG. 9 sets forth a partial section view taken along section line 9--9.
Distal end 78 of locating tabs 71 are shown against funnel end 20 of
syringe bore 14. Locking tabs 72 are shown at a distance of approximately
0.06 inches in the proximal direction from distal end 78 of locating tab
71. Expansion/contraction joint 78 is shown in its median position.
Anchoring tabs 73 are shown as outwardly extending sections of annulus
body 76 and dig into syringe bore 14 at 75 when movement in the proximal
direction is attempted.
FIG. 10 sets forth an alternate embodiment of the present invention whereby
annulus 80 is located at a position from funnel end 20 such that locking
tabs 82 will lock behind piston pushing flange 36 of piston driver 30 when
piston 40 is moved to funnel end 20 of syringe bore 14 at the completion
of giving an injection. Annulus 83 is bonded to syringe bore 14 at 84.
In each of the embodiments shown, the annulus is located within a
hypodermic syringe in a position where, when the injection is completed,
the piston driver is locked in the closed position and cannot be withdrawn
to be used to give another injection.
While particular embodiments of the invention have been shown and
described, it will be obvious to those skilled in the art that changes and
modifications may be made without departing from the invention in its
broader aspects. For example, it is obvious that sharp points could be
incorporated in the faces of both locking tabs and anchoring tabs in order
to engage the piston and barrel wall more readily. It is also obvious that
other edges could be rounded and/or angled to make the passage of the
piston in the distal direction easier.
Therefore the aim in the appended claims is to cover all such changes and
modifications as fall within the true spirit and scope of the invention.
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